Polishing pad release liner system

ABSTRACT

A polishing pad for planarizing and polishing a semiconductor substrate. The polishing pad ( 22 ) includes an adhesive layer ( 34 ) that is operative to adhere the polishing pad to a polishing fixture. To protect the adhesive layer from contamination during storage and shipment, a release liner ( 24 ) is placed over the adhesive layer. The release liner has sufficient surface characteristics to stay in adhesive connection with the adhesive layer during storage and shipment; however, the release liner is operative to be peeled away from the adhesive layer without disturbing the bond between the polishing pad and the adhesive layer. To aid in the removal of the release liner from the polishing pad, the release liner includes a pull tab ( 26 ). The pull tab is comprised of a single-sided tape that is adhered to the outer surface of the release liner. A portion ( 28 ) of the pull tab extends beyond the edge of the release liner. This extending portion has sufficient length to enable an operator of the polishing fixture to remove the release liner from the polishing pad while wearing gloves.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/201,634 filed May 3, 2000.

TECHNICAL FIELD

[0002] This invention relates to chemical mechanical polishing systems. Specifically this invention relates to features of a polishing pad for facilitating easier removal of a release liner.

BACKGROUND ART

[0003] Integrated circuits are typically fabricated from semiconductor wafers. The surfaces of semiconductor wafers are finely polished and planarized using chemical mechanical polishing (CMP) processes. Many of these polishing processes use a polishing fixture that includes a revolving belt or disc. The belt or disk of a polishing fixture is operative to accept one or more polishing pads that are adhered to the outer surfaces of the belt or disc. When a substrate such as a semiconductor wafer is placed adjacent the moving belt or disc, the polishing pad is operative to polish and planarize the surface of the wafer.

[0004] Polishing pads include an adhesive layer. The adhesive layer is comprised of a pressure sensitive adhesive (PSA) that is operative to adhere the polishing pad to a belt or disc of a polishing fixture. Polishing pads are manufactured with a protective release liner that overlies the adhesive layer of the polishing pad. The release liner is typically comprised of a flexible plastic planar membrane which must be peeled away from the adhesive layer prior to mounting the polishing pad to a polishing fixture. The release liner is designed to protect the adhesive layer from contamination during storage and shipment of the polishing pad.

[0005] Unfortunately, operators of polishing fixtures typically wear cumbersome rubber gloves which make removal of the release liner from the polishing pad very difficult. Many operators use either a sharp knife to lift the release liner from the polishing pad or fold the pad back against the release liner to force portions of the release liner away from the adhesive layer. Using a knife increases the opportunity for the operator to either damage the polishing pad or injure himself/herself. Also, folding the pad may cause a crease which can significantly decrease the pad's operational lifetime. Consequently there exists a need for a polishing pad that includes features for assisting in the removal of the release liner that are safer and less apt to damage the polishing pad.

[0006] Some polishing pads have been designed which include a release liner with portions that extend beyond the edges of the underlying surfaces of the polishing pad. In other designs, underlying portions of the polishing pad have been cut to extend beyond the edge of the release liner. Such extending portions may aid in the removal of the release liner from the underlying pad.

[0007] Unfortunately, to manufacture a polishing pad with a release liner that is a different shape than the underlying polishing pad, special cutting dies are required. In the case of a release liner that is larger than the underlying pad surfaces, exact cutting pressure is required to cut the pad without cutting the release liner. In the case of a polishing pad that includes portions that extend beyond the edge of the release liner, such portions must be trimmed from the pad prior to mounting the pad on a polishing fixture. These prior art features significantly increase the complexity and cost of manufacturing and mounting polishing pads. Consequently, there further exists a need for a polishing pad that includes features for removing the release liner which do not significantly increase the complexity and cost of manufacturing polishing pads.

DISCLOSURE OF INVENTION

[0008] It is an object of the present invention to provide a polishing pad for the polishing of semiconductor wafers.

[0009] It is a further object of the present invention to provide a release liner for a polishing pad that is easier and safer to remove.

[0010] It is a further object of the present invention to provide a polishing pad release liner that is easier to remove without damaging the polishing pad.

[0011] It is a further object of the present invention to provide a polishing pad release liner that can be easily removed while wearing gloves.

[0012] It is a further object of the present invention to provide a polishing pad which can be manufactured without special cutting dies.

[0013] It is a further object of the present invention to provide a polishing pad which does not include portions that must be cut and trimmed away from the polishing pad prior to mounting on a polishing fixture.

[0014] It is a further object of the present invention to provide a polishing pad that includes cost effective features for aiding in the removal of a release liner.

[0015] Further objects of the present invention will be made apparent in the following Best Modes for Carrying Out Invention and the appended claims.

[0016] The foregoing objects are accomplished in one exemplary embodiment of the invention by a polishing pad release liner that includes a single-sided adhesive tape adhered to the outer surface of the release liner. In the exemplary embodiment, a portion of the tape extends beyond the edge of the release liner to act as a pull tab. The extending portion may be pulled by an operator to remove the release liner from the polishing pad

[0017] The tape includes a pressure sensitive adhesive that provides a stronger bond with the release liner than the bond of the polishing pad adhesive layer. In the exemplary embodiment a silicone adhesive is used which provides a bond that is between two to four times the continuing release value of the release liner from the polishing pad. Once the tape has been mounted to the release liner, that portion of the tape which extends beyond the edge of the release liner and pad may be folded onto itself to encapsulate the adhesive within the extending portion of the tape.

[0018] The resulting pull tab enables an operator to quickly remove the release liner from the polishing pad safely and without damaging the polishing pad. In addition such an exemplary pull tab can be provided, without significantly increasing the cost and complexity of manufacturing polishing pads.

BRIEF DESCRIPTION OF DRAWINGS

[0019]FIG. 1 is a perspective view representative of a polishing fixture that includes a polishing pad mounted to a polishing disk.

[0020]FIG. 2 is a cross-sectional view representative of a polishing pad and a release liner.

[0021]FIG. 3 is a top plan view representative of a polishing pad with an adhesive tape pull tab mounted to the release liner.

[0022]FIG. 4 is a cross-sectional view representative of a polishing pad with an adhesive tape pull tab mounted to the release liner.

BEST MODES FOR CARRYING OUT INVENTION

[0023] Referring now to the drawings and particularly to FIG. 1, there is shown therein a perspective view representative of an exemplary polishing fixture 1 0. The polishing fixture 10 includes a disk 12 that is operative to rotate. Mounted to the disk 12 is a polishing pad 14. When a semiconductor wafer is placed adjacent the polishing pad, the relative movement between surfaces of the pad and the wafer facilitates polishing and planarizing of the wafer.

[0024]FIG. 2 shows an exemplary prior art polishing pad 16 prior to being mounted to a polishing fixture. The polishing pad 16 is manufactured with an adhesive layer 18 which facilitates adhesion of the pad 16 to a polishing fixture. However to prevent contamination of the adhesive layer 18 during shipment and storage, the polishing pad 16 is manufactured with a protective release liner 20 over the adhesive layer 18. The protective release liner 20 is typically comprised of a flexible plastic sheet that is operative to peel away from the adhesive layer 18 without disturbing the bond between the polishing pad 16 and the adhesive layer 18.

[0025]FIG. 3 shows a top plan view representative of an exemplary disk shaped polishing pad 22 of the present invention. To enable easier removal of the release liner 24 from the polishing pad 22, the release liner of the present exemplary invention includes a pull tab 26 mounted thereto. A portion 28 of the pull tab extends beyond the edge of the release liner and polishing pad. The extending portion 28 has sufficient length to enable an operator wearing gloves to grasp the pull tab. In the exemplary embodiment the extending portion 28 extends between 0.5 inches and 2.0 inches in length from the edge of the release liner 24. The exemplary width of the pull tab ranges between 0.5 inches and 1.0 inches. The length of the portion 29 of the pull tab that is mounted to the release liner 24 ranges between 1.0 inch and 4.0 inches. However, it is to be understood that alternative embodiments of the pull tab may have other dimensions depending on the size and shape of the release liner and the adhesive bond between the pull tab 26 and the release liner 24.

[0026] As shown in FIG. 4, the pull tab 26 is mounted to the release liner 24 by affixing the pull tab 26 to the upper surface of the release liner 24. In the exemplary embodiment, the pull tab 26 is comprised of a single-sided adhesive tape. Adhesive Tape No. 253 supplied by 3M is an example of one adhesive tape that is operative for use in the present invention. The exemplary adhesive tape 26 is comprised of a paper backing substrate 32 that includes an adhesive layer 30 comprised of a pressure sensitive silicon adhesive.

[0027] Alternative embodiments of the tape backing 32 may be comprised of other materials such as a flexible plastic sheet or a woven material. In addition the present invention encompasses any adhesive for the adhesive layer 30 that is operative to create a stronger bond between the tape backing 32 and the release liner 24 than the bond between the adhesive layer 34 of the polishing pad and the release liner 24. This relatively stronger bond of the adhesive layer 30 enables the tape to be used as a pull tab for peeling the release liner 24 from the polishing pad 36. In the exemplary embodiment the adhesive layer 32 between the pull tab 26 and the release liner 24 forms a bond that is between two to four times the continuing release value of the release liner from the polishing pad 24.

[0028] Although the exemplary embodiment encompasses a single-sided tape for the pull tab, alternative embodiments may use other non-tape materials such as a flexible paper or plastic that is may not be pre-manufactured with an adhesive layer. In such cases, when the pull tab is mounted to the release liner, a separate adhesive may be placed between the pull tab and the release liner for bonding the elements together.

[0029] As shown in FIG. 4, in one exemplary embodiment, the extending portion 28 includes an adhesive layer 30 that is encapsulated between a first protective layer 38 and a second protective layer portion 40. In this described embodiment the extending portion is folded back on itself to have the backing of the adhesive tape form the first and second protective layers 38 and 40. In an alternative exemplary embodiment, rather than folding the extended portion 28, the second portion 40 may be comprised of a separate material. For example, the second portion 40 may be comprised of a separate uncoated paper or film that is bonded to the adhesive layer 30 of the extending portion 28. In each of these described embodiments, the encapsulation of the adhesive layer 30 on the extending portion 28 facilitates fabrication, application, and handling of the tab stock, and prevents the pull tab from adhering to unintended objects.

[0030] Thus the polishing pad release liner system achieves the above stated objectives, eliminates difficulties encountered in the use of prior devices and systems, solves problems and attains the desirable results described herein.

[0031] In the foregoing description certain terms have been used for brevity, clarity and understanding, however no unnecessary limitations are to be implied therefrom because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the descriptions and illustrations herein are by way of examples and the invention is not limited to the exact details shown and described.

[0032] In the following claims any feature described as a means for performing a function shall be construed as encompassing any means known to those skilled in the art to be capable of performing the recited function, and shall not be limited to the structures shown herein or mere equivalents thereof.

[0033] Having described the features, discoveries and principles of the invention, the manner in which it is constructed and operated, and the advantages and useful results attained; the new and useful structures, devices, elements, arrangements, parts, combinations, systems, equipment, operations, methods and relationships are set forth in the appended claims. 

I claim:
 1. A semiconductor substrate polishing system comprising: a polishing pad, wherein the polishing pad includes a first adhesive layer that is operative to adhere the polishing pad to a polishing fixture; a release liner in operative adhesive connection with the first adhesive layer; and a pull tab in operative adhesive connection with the release liner, wherein the pull tab extends beyond an edge of the release liner.
 2. The semiconductor substrate polishing system according to claim 1 , further comprising a second adhesive layer between the pull tab and the release liner, wherein the second adhesive layer is operative to create a sufficient bond between the pull tab and the release liner to enable an operator to release the release liner from the polishing pad by pulling the pull tab.
 3. The semiconductor substrate polishing system according to claim 2 , wherein the bond between the pull tab and the release liner is between two to four times the continuing release value of the release liner from the pad.
 4. The semiconductor substrate polishing system according to claim 2 , wherein the pull tab includes an adhesive tape.
 5. The semiconductor substrate polishing system according to claim 4 , wherein the pull tab includes a single-sided adhesive tape.
 6. The semiconductor substrate polishing system according to claim 4 , wherein the pull tab includes an extending portion that extends from the edge of the release liner, wherein, the extending portion includes a portion of the second adhesive layer, wherein the portion of the second adhesive layer is encapsulated between a first protective layer and a second protective layer.
 7. The semiconductor substrate polishing system according to claim 6 , wherein the first protective layer is comprised of a backing layer of the adhesive tape.
 8. The semiconductor substrate polishing system according to claim 6 , wherein the extending portion is folded, where the first and second protective layers correspond to a backing layer of the adhesive tape.
 9. The semiconductor substrate polishing system according to claim 2 , wherein the pull tab includes an extending portion that extends between 0.5 inches and 2.0 inches in length from the edge of the release liner.
 10. The semiconductor substrate polishing system according to claim 9 , wherein the pull tab is between 0.5 inches and 1.0 inches in width.
 11. The semiconductor substrate polishing system according to claim 10 , wherein the pull tab includes a portion adhered to the release liner that is between 1.0 inch and 4.0 inches in length.
 12. The semiconductor substrate polishing system according to claim 2 , wherein the release liner has a shape and a size which corresponds to the polishing pad. 